Optical multiplexer and demultiplexer module including multiplexing and demultiplexing filter film

Abstract

A compact size optical multiplexer and demultiplexer module. The optical multiplexer and demultiplexer module includes a multiplexing and demultiplexing film disposed on an end surface of a waveguide substrate, having an optical waveguide formed thereon, on which surface an input and output end of the optical waveguide appears. The multiplexing and demultiplexing film transmits a light beam of wavelength λ 1 and reflects a light beam of wavelength λ 2 . A first optical fiber is disposed such that a light beam with the wavelength λ 1 propagated therethrough is coupled to the input and output end of the waveguide substrate after being transmitted through the multiplexing and demultiplexing film and the second optical fiber is disposed such that a light beam with the wavelength λ 2 propagated therethrough is coupled to the first optical fiber after being reflected by the multiplexing and demultiplexing film. A light beam with the wavelength λ 1 from the first optical fiber is transmitted through the multiplexing and demultiplexing film and sent to a photodiode and a light beam with the wavelength λ 1 from a laser diode is transmitted through the multiplexing and demultiplexing film and sent to the first optical fiber. A light beam with the wavelength λ 2 from the second optical fiber is reflected by the multiplexing and demultiplexing film and sent to the first optical fiber.

What is claimed is: 
     
       1. An optical multiplexer and demultiplexer module comprising: a waveguide substrate on which a waveguide is formed;   a multiplexing and demultiplexing filter film provided on an end surface of said waveguide substrate, on which surface an input and output end of said optical waveguide appears, for transmitting a first wavelength and reflecting a second wavelength;   a first optical fiber arranged such that a light beam with said first wavelength propagated therethrough is coupled to said optical waveguide on said waveguide substrate after being transmitted through said multiplexing and demultiplexing filter film; and   a second optical fiber arranged such that a light beam with said second wavelength propagated therethrough is coupled to said first optical fiber after being reflected by said multiplexing and demultiplexing filter film.   
     
     
       2. An optical multiplexer and demultiplexer module according to claim 1, wherein said first optical fiber and said second optical fiber have their front ends shaped into a spherical form and are arranged slightly apart from said multiplexing and demultiplexing filter film.   
     
     
       3. An optical multiplexer and demultiplexer module according to claim 1, wherein end faces of said first optical fiber and said second optical fiber are adhesively attached to said multiplexing and demultiplexing filter film.   
     
     
       4. An optical multiplexer and demultiplexer module according to claim 3, wherein said first optical fiber and said second optical fiber are obliquely cut in the vicinity of their front end faces such that said front end faces are partly left uncut and said obliquely cut faces are joined together, whereby front ends of the cores of said first optical fiber and said second optical fiber are joined together.   
     
     
       5. An optical multiplexer and demultiplexer module according to claim 1, wherein the end surface, on which said multiplexing and demultiplexing filter film is formed, of said waveguide substrate is oriented such that the normal line to said end surface forms an angle of θ 0  with said optical waveguide,   said first optical fiber and said second optical fiber are arranged on both sides of the normal line to said end surface, each forming an angle of θ 1  with the normal line, and   said angle θ 0  and said angle θ 1  are set so as to substantially satisfy the relationship   sinθ1=n.sinθ.sub.0,     where n is the refractive index of said optical waveguide.     
     
     
       6. An optical multiplexer and demultiplexer module according to claim 1, wherein said first optical fiber is coupled to said optical waveguide through a first lens, and   said second optical fiber is coupled to said first optical fiber through a second lens.   
     
     
       7. An optical multiplexer and demultiplexer module according to claim 6, wherein said first optical fiber and the center axis of said first lens are arranged to be out of alignment, and said second optical fiber and the center axis of said second lens are arranged to be out of alignment, whereby said first optical fiber and said second optical fiber are arranged substantially parallel to each other.   
     
     
       8. An optical multiplexer and demultiplexer module according to claim 5, further comprising: a first substrate in which a pair of V grooves are formed, said V grooves forming the same angle therebetween as the angle to be formed between said first optical fiber and said second optical fiber; and   a second substrate on which said first substrate and said waveguide substrate are to be fixed, wherein   said first optical fiber and said second optical fiber are disposed along their respective V grooves and then fixed to said first substrate, and   said first substrate and said waveguide substrate are disposed so as to satisfy said predetermined relationship and then fixed to said second substrate.   
     
     
       9. An optical multiplexer and demultiplexer module according to claim 8, wherein the surfaces around the front end portions of said first optical fiber and said second optical fiber and the surfaces of said V grooves are coated with metallic plating, and   said first optical fiber and said second optical fiber are fixed at their metal-plated portions to said V grooves formed in said first substrate by soldering.   
     
     
       10. An optical multiplexer and demultiplexer module according to claim 8, wherein said first substrate and said waveguide substrate are fixed to said second substrate by soldering.   
     
     
       11. An optical multiplexer and demultiplexer module comprising: a waveguide substrate, on which an optical waveguide is formed, having a slit formed therein such that the input and output end of said optical waveguide appears on a surface of said slit and having a first V groove and a second V groove formed therein so as to form predetermined angles with said slit;   a multiplexing and demultiplexing filter film provided on the surface of said slit formed in said waveguide substrate, on which surface said optical waveguide appears, for transmitting a first wavelength and reflecting a second wavelength;   a first optical fiber arranged along and fixed to said first V groove such that a light beam with said first wavelength propagated therethrough is coupled to said optical waveguide on said waveguide substrate after being transmitted through said multiplexing and demultiplexing filter film; and   a second optical fiber arranged along and fixed to said second V groove such that a light beam with said second wavelength propagated therethrough is coupled to said first optical fiber after being reflected by said multiplexing and demultiplexing filter film.   
     
     
       12. an optical multiplexer and demultiplexer module according to claim 11, wherein said slit is formed such that the normal line thereof forms an angle of θ 0  with said optical waveguide,   said first V groove and said second V groove are arranged on both sides of the normal line to said slit, each forming an angle of θ 1  with the normal line, and   said angle θ 0  and said angle θ 1  are set so as to substantially satisfy the relationship   sinθ.sub.1 =n.sinθ.sub.0,     where n is the refractive index of said optical waveguide.     
     
     
       13. An optical multiplexer and demultiplexer module according to claim 11, wherein the surfaces around the front end portions of said first optical fiber and said second optical fiber and the surfaces of said first V groove and said second V groove are coated by metallic plating, and   said first optical fiber and said second optical fiber are arranged along said first V groove and said second V groove and are fixed at their metal plated portions to said waveguide substrate by soldering.